Question to the Foreign, Commonwealth & Development Office:

To ask Her Majesty’s Government which of the 28 member states of the European Union are required to hold a referendum before they approve either a new treaty or an amendment to an existing treaty.

The EU has adopted new treaties, and amended existing ones, since the original Treaty of Rome in 1957. These changes have reflected the evolution of EU business. Developments in the Eurozone are likely to create the conditions for further treaty change in the future.

A number of different factors determine whether an EU Member State is required to hold a national referendum before approving a new EU treaty or an amendment to an existing EU Treaty. These factors include Constitutional obligations, legal or political precedent and the nature of the treaty or treaty change. In the UK, the European Union Act 2011 sets out the circumstances in which treaties amending or replacing the EU Treaties require prior approval by referendum.